Currently, efficacious treatment of human beings infected with HIV is best accomplished by use of a mixture, or cocktail, of different drugs that act as inhibitors of key enzymes that control different stages in viral development, assembly and/or propagation. Integral drugs in that cocktail are the HIV Specific Protease inhibitors saquinavir and ritonavir. Immunoassay analysis of saquinavir and ritonavir would provide an analytically suitable, clinically useful therapeutic monitoring methodology. Fluorescence polarization immunoassays (FPIA) represent a suitable method for these types of measurements that has proven especially useful and cost effective in monitoring anti infectives. Two milestones are extant in this proposal: (1) Preparation of the poly/monoclonal immunoreagents and fluorescent tracers used in FPIA and (2) Demonstration of the feasibility and suitability of those reagents in an automated assay paradigm. PROPOSED COMMERCIAL APPLICATION: Measurement of HIV Protease Inhibitors will become a standard of treatment in the application of these drugs in my. Providing a cost effective and efficient analytical methodology, such as FPIA. Provision of that measurement will greatly enhance the efficacious use of these drugs.